The half-life for a 100-gram sample of radioactive element X is 5 days. How much of element X remains after 10 days have passed?

Question

a
25 g
b
10o g - no change
c
50 g
d
12.5 g

Answer 1

The half-life of a substance is the time it takes for half of the substance to decay. For element X, the half-life is 5 days.

After:

• 5 days: 100 g → 50 g (first half-life)
• 10 days: 50 g → 25 g (second half-life)

So, after 10 days, 25 grams of element X remains.

The answer is a) 25 g.